1. Field of the Invention
The present invention relates to junction of a spacer of a field emission display, and in particular to a junction method of a spacer in a field emission display, and the field emission display which can enhance an adhesive strength between a spacer and an anode substrate, and overcome the charging and arcing problem of electrons due to collision of the electrons and a frit material, by printing the frit before depositing a metal-back thin film.
2. Description of the Related Art
Recently, a field emission display (FED) has been actively developed. The FED provides excellent image quality like a cathode ray tube even in a thin film structure such as a liquid crystal display (LCD) or plasma display panel (PDP).
FIG. 1 is a diagram illustrating a structure of a general FED.
Referring to FIG. 1, the FED includes: an anode substrate 100; a cathode substrate 110; and a spacer 120 for supporting a vacuum gap between the two substrates.
The FED is divided into a low voltage type FED and a high voltage type FED.
The low voltage type FED is driven by applying a low anode voltage of 400 to 1000V to an anode electrode. The low voltage type FED has advantages in that the spacer for maintaining the vacuum gap can be easily designed and formed, and that a material can he flexibly selected. However, light emission efficiency of a currently-used low voltage fluorescent material is low. and concentration of electrons is not active.
In order to solve the foregoing problems, there has been suggested the high voltage type FED. Advantageously, the high voltage type FED can employ a general fluorescent material for a cathode ray tube operated at a high voltage as it is.
Conversely, as compared with the low voltage type FED, a high voltage (1 kV to 10 kV) should be applied to the anode substrate 100 for concentration of an electron beam. Accordingly, the anode substrate 100 and the cathode substrate 110 maintain an interval of at least 1 mm due to application of the high voltage.
An aspect ratio of the spacer structure is increased over 1:20 to satisfy such an additional limit condition. It is thus difficult to precisely align the spacer 120 between the pixels due to the high aspect ratio of the spacer.
In order to overcome such difficulties, there have been suggested methods for forming a spacer in various shapes.
For example, suggested are a method for aligning a rib type spacer by using an auxiliary grip, and a method for precisely forming a groove on an anode substrate and inserting a spacer into the groove. In addition, there is a method for processing a spacer in various shapes by using a photoresist glass.
FIGS. 2A to 2C are diagrams illustrating a conventional junction method of a spacer.
FIG. 2A shows a method for aligning a rip type spacer 210 by using an auxiliary ceramic grip 220 and a polyimide grip 230.
FIG. 2B shows a method for precisely forming a groove on a cathode substrate 240, and inserting the rip type spacer 210 into the groove.
FIG. 2C shows a method for processing the spacer in various shapes by using the photoresist glass.
In the aforementioned methods, the auxiliary grips 220 and 230 prevent vacuum exhaust, or a complicated process is added for spacer processing or junction. Furthermore, application technologies of the methods are also difficult.
In order to overcome such technical difficulties, there is suggested a method for printing a junction material such as a frit glass on the anode substrate or cathode substrate, and aligning and holding the spacer, without using the auxiliary grips 220 and 230. Especially in the junction method which the junction material is used, the spacer is bonded to the anode substrate to prevent the cathode substrate from being damaged due to a post heat process.
During the process of the anode substrate, a metal-back thin film is deposited on emulsion, and then the emulsion is removed to planarize the surface. Generally, the emulsion is removed according to a heat process. However, the metal-back material comes off the upper portion of the anode substrate by the emulsion removing process, and thus has a very low adhesive strength.
That is, when the frit for the junction of the spacer is printed on the metal-back thin film, the adhesive property of the metal-back thin film is deteriorated. As a result, the adhesive strength of the spacer is also reduced.
It is, therefore, an object of the present invention to provide a junction method of a spacer in a field emission display for preventing charging and arching of electrons by printing a frit before depositing a metal-back thin film.
To achieve the above object, there is provided a junction method of a spacer in a field emission display including the steps of: forming a fluorescent material on an anode substrate; coating emulsion which is a planarization layer thereon; forming a frit at a predetermined position on the emulsion; depositing a metal-back thin film thereon; and aligning and bonding the spacer on the anode substrate.
In another aspect of the present invention, in the process for forming the fluorescent material, a black matrix is formed by patterning the fluorescent material on the substrate, the frit is printed on the black matrix, and a binder included in the frit is removed according to a heat process.
In a yet another aspect of the present invention, the metal-back thin film is planarized, the emulsion is removed, and preliminary sintering of the frit is performed at the same time, by executing a heat process after depositing the metal-back thin film.
In a yet another aspect of the present invention, in the step for aligning and bonding the spacer, the spacer is aligned on the frit area, and bonded thereto according to a heat process.
In a yet another object of the present invention, there is provided a junction method of a spacer in a field emission display including the steps of: forming a fluorescent material on an anode substrate; forming a frit at a predetermined position on the fluorescent material; coating emulsion which is a planarization layer on the fluorescent material; depositing a metal-back thin film on the emulsion; and aligning and bonding the spacer on the anode substrate.